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automatic shutdown of plasma

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salong

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Joined: Thu Jun 11, 2015 2:47 pm

Post Thu Jul 09, 2015 11:51 pm

automatic shutdown of plasma

With our CyTOF1, we have had sporadic automatic shutdown of our plasma but it was rare enough that it was difficult to troubleshoot. Now, it is happening more often (2-3 times/day). We are waiting for a new skimmer/reducer cone to ship. However, we are wondering if others are experiencing automatic shutdowns of plasma and if so, at what frequency and do you know the cause?
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mleipold

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Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Mon Jul 13, 2015 3:14 pm

Re: automatic shutdown of plasma

Hi Alice,

What error message are you getting in the Instrument Set-up window?


Mike
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TomerWeizmann

Contributor

Posts: 43

Joined: Mon Apr 07, 2014 11:58 am

Location: Weizmann Institute of Science - Israel

Post Mon Jul 13, 2015 3:42 pm

Re: automatic shutdown of plasma

Hi Alice,
We had similar symptoms with our CyTOF2.
Assuming there are no issues with gas and carrier flows resulting in accumulation of water in the system extinguishing the plasma (a simple way to check this is to run a ‘dry plasma’ by blocking the spray chamber without the nebulizer etc.)…
Our malfunction was finally resolved by replacement of the RFG.
Tomer
Dr. Tomer-Meir Salame
Head, Mass Cytometry Unit
Life Sciences Core Facilities
Weizmann Institute of Science
E-mail: tomer-meir.salame@weizmann.ac.il
https://www.weizmann.ac.il/LS_CoreFacil ... etry/about
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mleipold

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Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue Jul 14, 2015 10:31 pm

Re: automatic shutdown of plasma

Hi Alice,

Do you know what error message you're getting in the Instrument Set-Up window when you get a plasma shutdown on your CyTOFv1?

For example, "RFG went from PLASMA MODE to READY MODE" is usually a sign of a nebulizer clog.


Mike
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salong

Participant

Posts: 6

Joined: Thu Jun 11, 2015 2:47 pm

Post Tue Jul 28, 2015 2:46 pm

Re: automatic shutdown of plasma

Hi all, thanks for the input! We never got an error message and tried running a dry plasma, but these things did not direct us to a solvable issue.

Daniel from Fluidigm came out and did a full overhaul of our machine. The likely culprit for lack of plasma stability was a decrease in our exhaust pressure. Do others monitor exhaust pressure over-time, and if so, at what frequency?

Thanks!
Alice
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue Jul 28, 2015 2:59 pm

Re: automatic shutdown of plasma

Hi Alice,

We don't monitor our exhaust on too regular a basis. For CyTOFv1 machines, we often get a T2 temperature warning a couple hours into a run if there's an exhaust problem.

For our third machine, we installed magnehelic pressure gauges in-line with both exhaust lines. That way, we can monitor on the fly. They're not cheap, but I know of a number of other groups who have done that as well.


Mike
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zebrafish

Participant

Posts: 7

Joined: Wed Nov 05, 2014 11:47 am

Post Tue Jul 28, 2015 3:39 pm

Re: automatic shutdown of plasma

We have the same issue here at Penn, with CyTOF2. Plasma shut down. I was told this is because of microclogging? Not sure. But if we restart the plasma, everything will be fine. Also, sometimes we pull out the nebulizer to check for clogging when plasma shut down. If we do so, once we restart the CyTOF, do we need to redo the calibration?
Thank you!
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue Jul 28, 2015 5:51 pm

Re: automatic shutdown of plasma

Plasma can be shut down because of a partially clogged nebulizer. Basically, a clog forms, fluid flow is hindered, pressure builds, and then bursts through. This causes a large amount of liquid to spray out, which overwhelms the plasma stability and it shuts down (I'll let Fluidigm go into more detail regarding flow rate, liquid volume, and plasma stability).

Generally speaking, this will give you an error message something like "RFG went from PLASMA MODE to READY MODE."

If this happens, you can usually immediately restart the machine. Sometimes, this may take more than one attempt, depending on how much liquid sprayed out (and therefore may be lingering in the glassware to interfere with plasma ignition). As soon as possible, run Wash solution or 3% nitric to clear the clog. Or, before start-up, replace the nebulizer with a clean nebulizer.

You shouldn't have to re-do the calibration if you just swap a nebulizer. About the only way I could think that you would need to is if the nebulizer was clogged from the start, and so your make-up gas value would reflect how much the MG needed to change to efficiently force the mis-aligned spray into the machine.


Mike
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vtosevski

Contributor

Posts: 44

Joined: Wed Nov 20, 2013 12:50 pm

Location: Zurich, Switzerland

Post Tue Jul 28, 2015 8:40 pm

Re: automatic shutdown of plasma

Hi all,

Just to pick up on the notice of not having to re-tune after plasma going off (for whatever reason). Is this really the case? I've tried it (intentionally stopping plasma) and ran only minimal auto-tuning (mass and dual count calibration and QC) afterwards, getting values somewhat lower than with the initial tuning. Following it up with a complete tuning right away, I get better values (higher Tb count). Is this in the domain of randomness or should one maybe run a full tuning after plasma outage?

Vinko
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue Jul 28, 2015 8:53 pm

Re: automatic shutdown of plasma

Hi VInko,

Could you give us an example of those numbers?

In my experience, up to ~10% variance in Tb signal between days is standard. Beyond that, I start checking whether there's something wrong with the fluidics (partially clogged line or nebulizer).


Mike

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